By the 1790s, Belen had established a city center known as Plaza Vieja, or Old Town, and had grown from a paraje, or precinct, to a partido, or district, with a population of 1,695. By the middle of the 19th century, Belen had outgrown Old Town and was expanding into what became known as New Town.In 1853, the residents in each part of town disagreed over the construction of a new Catholic church, with residents of Old Town wanting the new church to remain there, while residents of New Town wanted it built in their part of town.
In the late winter of 1862, Belen, an ally of the Union, become entangled in the Civil War when the town briefly fell under Confederate control after 400 Confederate soldiers marched into Belen.
Belen is at the southern end of the Albuquerque Metropolitan Statistical Area. Belen was founded in 1740 as Nuestra Señora de Belén by a group of Spanish colonists led by Diego Torres and Antonio Salazar, who received permission to settle the tract of land known as the Belen Grant the year before.
Recognizing the strategic significance of Belen, Spanish authorities established a fort in Belen to protect the settlements along the Rio Grande in 1760.
Old City Hall, also located on Becker Avenue, is a 1938 Works Progress Administration project, which housed the former Belen City Hall and fire department.
The two-story building was constructed of terron, a material similar to adobe.